/Engine/Source/Runtime/Core/Public/Math/Vector.h
See if two normal vectors are nearly parallel, meaning the angle between them is close to 0 degrees.
true if vectors are nearly parallel, false otherwise.
static bool Parallel ( const [TVector](API\Runtime\Core\Math\TVector)< T > & Normal1, const [TVector](API\Runtime\Core\Math\TVector)< T > & Normal2, T ParallelCosineThreshold )